University of Twente Student Theses


Reaction pathways in the dehydration of propyleneglycol over scandium oxide catalyst

Tjeerdsma, D. (2020) Reaction pathways in the dehydration of propyleneglycol over scandium oxide catalyst.

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Abstract:Biomass based chemicals are increasingly seen as an environmentally friendlier alternative to fossil fuels. As a result, propane polyols are becoming more widely available thanks to the deployment of bio-diesel plants. Propyleneglycol is a valuable chemical that can be upgraded by performing a dehydration to allyl alcohol and a subsequent oxidation reaction to acrylic acid. This route requires both catalyst and process optimization before coming industrially viable due to the limited yields achieved. The present research aims to develop a catalyst capable of reaching the selectivity and productivity required of an industrial catalyst. This research studied the dehydration of propyleneglycol over scandium oxide catalysts based on the excellent selectivity shown in the similar 2,3-butanediol dehydration reaction. A continuous Plug Flow Reactor was used to study the kinetics and behavior of the system. Samples were analyzed using HPLC to determine the concentration of products in the liquid sample. Our results show that under similar reaction conditions, the dehydration of propyleneglycol behaves significantly different when compared to 2,3-butanediol. Results suggest that the selectivity towards the unsaturated alcohol was lower for the propyleneglycol dehydration. It was determined that the dehydration towards the dehydration products follows first order behavior. The apparent activation barriers towards the main dehydration products were measured to be approximately 115kJ/mol. Significant selectivity to byproducts was measured over the scandium oxide catalyst. This study speculates on the fundamental reason for the discrepancy between dehydration reactions. Evaluation of the studied system reveals that the scandium oxide catalyst is not applicable in an industrial system. Additional work is required on improving the selectivity and reducing the total cost of the catalyst. The introduction of a support is an interesting area for further research. In addition, the fundamental difference between 2,3-butanediol and propyleneglycol remains speculation.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:35 chemistry
Programme:Chemical Engineering MSc (60437)
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